Nitrous oxide consumption potentials of well-drained forest soils in Southern Québec, Canada.

To establish the major controls on N2O consumption by forest soils, we conducted laboratory incubations of 16 samples from four soil types, two organic and two mineral, varying in overlying forest vegetation (sugar maple, American beech and eastern hemlock). The fastest potential consumption of N2O occurred under anoxic conditionswith little soil nitrate and under elevated headspaceN2O concentration. Potential N2O consumption rates were fastest in organic soils under hemlock and beech trees (111 and 75 ng N2O-Ng−1 d−1, respectively) compared to mineral soils under beech and maple trees (45 and 41 ng N2O-N g−1 d−1). Organic soils showed faster N2O consumption rates than mineral soils, possibly due to larger organic C levels and higher C:N ratios. Acetylene treatment confirmed that denitrification was the process underlyingN2Oconsumption. These results suggest that soils regularly consume N2O with varying magnitude, most likely in anoxic microsites throughout the soil profile and that the potential for N2O consumption is larger in organic than in mineral forest soils

Boundary conditions and Berry phase in magnetic nanostructures

The effect of micromagnetic boundary conditions on the Berry curvature and topological Hall effect in granular nanostructures is investi- gated by model calculations. Both free surfaces and grain boundaries between interacting particles or grains affect the spin structure. The Dzyaloshinskii-Moriya interactions yield corrections to the Erdmann-Weierstrass boundary conditions, but the Berry curvature remains an exclusive functional of the local spin structure, which greatly simplifies the treatment of nanostructures. An explicit example is a model nanostructure with cylindrical symmetry whose spin structure is described by Bessel function and which yields a mean-field-type Hall-effect contribution that can be related to magnetic-force-microscopy images

Spontaneous Lung Herniation Leading to Extensive Subcutaneous Emphysema, Pneumothorax, Pneumomediastinum, and Pneumopericardium.

Spontaneous lung herniation is a rare phenomenon in which the lung parenchyma along with the pleural membranes protrudes outside their usual boundaries and can lead to a wide variety of complications. We are reporting a case of a middle-aged male who presented with chronic obstructive pulmonary disease (COPD) exacerbation with severe bouts of cough. Initial computed tomography (CT) chest was unrevealing, but two days later, he developed spontaneous lung herniation, which was initially managed conservatively, but later it progressed to pneumothorax, pneumomediastinum, with striking CT scan images showing extensive subcutaneous emphysema. Blowhole incisions were done on the anterior chest wall which led to ultimate recovery

Near-thermal limit gating in heavily-doped III-V semiconductor nanowires using polymer electrolytes

Doping is a common route to reducing nanowire transistor on-resistance but has limits. High doping level gives significant loss in gate performance and ultimately complete gate failure. We show that electrolyte gating remains effective even when the Be doping in our GaAs nanowires is so high that traditional metal-oxide gates fail. In this regime we obtain a combination of sub-threshold swing and contact resistance that surpasses the best existing p-type nanowire MOSFETs. Our sub-threshold swing of 75 mV/dec is within 25% of the room-temperature thermal limit and comparable with n-InP and n-GaAs nanowire MOSFETs. Our results open a new path to extending the performance and application of nanowire transistors, and motivate further work on improved solid electrolytes for nanoscale device applications.Comment: 6 pages, 2 figures, supplementary available at journa

The influence of atmosphere on the performance of pure-phase WZ and ZB InAs nanowire transistors

We compare the characteristics of phase-pure MOCVD grown ZB and WZ InAs nanowire transistors in several atmospheres: air, dry pure N$_2$ and O$_2$, and N$_2$ bubbled through liquid H$_2$O and alcohols to identify whether phase-related structural/surface differences affect their response. Both WZ and ZB give poor gate characteristics in dry state. Adsorption of polar species reduces off-current by 2-3 orders of magnitude, increases on-off ratio and significantly reduces sub-threshold slope. The key difference is the greater sensitivity of WZ to low adsorbate level. We attribute this to facet structure and its influence on the separation between conduction electrons and surface adsorption sites. We highlight the important role adsorbed species play in nanowire device characterisation. WZ is commonly thought superior to ZB in InAs nanowire transistors. We show this is an artefact of the moderate humidity found in ambient laboratory conditions: WZ and ZB perform equally poorly in the dry gas limit yet equally well in the wet gas limit. We also highlight the vital role density-lowering disorder has in improving gate characteristics, be it stacking faults in mixed-phase WZ or surface adsorbates in pure-phase nanowires.Comment: Accepted for publication in Nanotechnolog

Phytochemical analysis of selected medicinal plants

Four medicinal plants including Ranunculus arvensis, Equisetum ravens, Carathamus lanatus and Fagonia critica were used for the study. All the plants were biologically active and were used for different types of ailments. Keeping in view their importance, this work was carried out to investigate the quantitative determination of their crude phytochemicals, vitamins and protein contents. The quantitative determination of crude phytochemicals (alkaloids, total phenols, flavonoids and saponins) vitamins (riboflavin, vitamin C, niacin and pectin) and protein were determined in the aforementioned herbs. The phytochemicals including alkaloids, total phenols, flavonoids and saponins were determined quantitatively using literature methods. Vitamins were measured using a UV/ visible spectrophotometer (UV- 1601 Shamidzu) and the protein was determined by the Micro KJeldahl’s method (Horwitz et al., 2000). The studied plants showed variable amounts of phytochemicals, vitamins and protein contents. The study is very important, in that it intended to show the contents of the studied medicinal herbs and also provide a scientific data base line which is of particular importance for the local practioners as well as for the local people using these herbs for a variety of body disorders.Key word: Phytochemical analysis, medicinal plants, Pakistan

Towards low-dimensional hole systems in Be-doped GaAs nanowires

GaAs was central to the development of quantum devices but is rarely used for nanowire-based quantum devices with InAs, InSb and SiGe instead taking the leading role. p-type GaAs nanowires offer a path to studying strongly-confined 0D and 1D hole systems with strong spin-orbit effects, motivating our development of nanowire transistors featuring Be-doped p-type GaAs nanowires, AuBe alloy contacts and patterned local gate electrodes towards making nanowire-based quantum hole devices. We report on nanowire transistors with traditional substrate back-gates and EBL-defined metal/oxide top-gates produced using GaAs nanowires with three different Be-doping densities and various AuBe contact processing recipes. We show that contact annealing only brings small improvements for the moderately-doped devices under conditions of lower anneal temperature and short anneal time. We only obtain good transistor performance for moderate doping, with conduction freezing out at low temperature for lowly-doped nanowires and inability to reach a clear off-state under gating for the highly-doped nanowires. Our best devices give on-state conductivity 95 nS, off-state conductivity 2 pS, on-off ratio ~$10^{4}$, and sub-threshold slope 50 mV/dec at T = 4 K. Lastly, we made a device featuring a moderately-doped nanowire with annealed contacts and multiple top-gates. Top-gate sweeps show a plateau in the sub-threshold region that is reproducible in separate cool-downs and indicative of possible conductance quantization highlighting the potential for future quantum device studies in this material system